To provide a rubber composition which can produce a rubber product excellent in tensile strength, wear resistance and dynamic characteristics.

The rubber composition comprises (A) 20-80 wt.% of a nitrile group-containing copolymer rubber having an iodine value of 100 or lower and a content of α,β-ethylenically unsaturated nitrile monomer units of 10-60 wt.% and (B) 80-20 wt.% of a chlorosulfonated polyolefin having a glass transition temperature of -25°C or lower.